Saw device having acoustic elements with diverse mass loading and method for forming same

Abstract

A surface acoustic wave device (100), includes a piezoelectric substrate (105) having a surface acoustic wave structure with an acoustic region (130). An acoustic element (115) disposed in a portion (110) of the acoustic region (130), has a different mass loading than an acoustic element (122) disposed in another portion (120) of the acoustic region (130).

What is claimed is: 
     
       1. A surface acoustic wave (SAW) device, comprising: a piezoelectric substrate; and   a first SAW transducer disposed on the piezoelectric substrate, the first SAW transducer having a plurality of interdigitated transducer fingers including first and second distinct portions that have a common acoustic track;   wherein the first portion is located at an edge of the transducer along the common acoustic track, and consists of a plurality of adjacent transducer fingers each having a metallization thickness in height greater than that of each finger in the second portion.   
     
     
       2. The surface acoustic wave device of claim 1, further comprising: a second SAW transducer disposed on the piezoelectric substrate, the second SAW transducer having first and second portions each consisting of a plurality if adjacent transducer fingers, the first portion of the second SAW transducer being adjacent to the first portion of the first SAW transducer, wherein each transducer finger of the first of the first portion of the second SAW transducer has a metallization thickness in height greater than that of the transducer fingers in the second portion of the second SAW transducer.   
     
     
       3. A surface acoustic wave (SAW) device, comprising: a piezoelectric substrate; and   a SAW structure disposed on the piezoelectric substrate, the SAW structure comprising at least three acoustic elements in series having successive acoustic elements each with a successive incremental increase in metallization height.   
     
     
       4. A surface acoustic wave (SAW) device, comprising: a first interdigitated SAW transducer disposed on a piezoelectric substrate, the first interdigitated SAW transducer having first and second portions in a common acoustic track, each of the first and second portions consisting of adjacent transducer fingers, the first portion of the first interdigitated SAW transducer being located at an edge of the transducer within the common acoustic track, said first portion having each transducer finger with a metallization height different than that of the transducer fingers of the second portion of the first interdigitated SAW transducer.   
     
     
       5. The surface acoustic wave device of claim 4, wherein the first interdigitated SAW transducer has at least three successive fingers each with a successive incremental increase in metallization height. 
     
     
       6. The surface acoustic wave device of claim 4, further comprising: a second interdigitated SAW transducer disposed on the piezoelectric substrate, the second interdigitated SAW transducer having first and second portions each consisting of adjacent transducer fingers, the first portion of the second interdigitated SAW transducer being located adjacent to the first portion of the first interdigitated SAW transducer, the first portion of the second interdigitated SAW transducer having each transducer finger with a metallization height different than that of the transducer finger of the second portion of the second interdigitated SAW transducer.   
     
     
       7. A surface acoustic wave (SAW) device, comprising: a piezoelectric substrate; and   a first SAW transducer disposed on the piezoelectric substrate, the first SAW transducer having a plurality of interdigitated transducer fingers including first and second distinct portions that have a common acoustic track;   wherein the first portion is located at an edge of the transducer within the common acoustic track, and consists of a plurality of adjacent transducer fingers each formed from a material different than that of each finger in the second portion.   
     
     
       8. The surface acoustic wave device of claim 7, further comprising: a second SAW transducer disposed on the piezoelectric substrate, the second SAW transducer having first and second portions each consisting of a plurality of transducer fingers, the first portion of the second SAW transducer being adjacent to the first portion of the first SAW transducer, wherein each transducer finger of the first portion of the second SAW transducer is formed a material different than that of the transducer fingers in the second portion of the second SAW transducer.